Display device and display method for display device

ABSTRACT

A display device provided in a vehicle that travels autonomously includes: a display unit configured to display information to an outside of the vehicle; a determination unit configured to determine whether a travel state of the vehicle is any one of a deceleration state, a stop state, and a start state, based on a detection result of an internal sensor of the vehicle; and a display control unit configured to display on the display unit the information corresponding to each of the deceleration state, the stop state, and the start state, based on a determination result of the determination unit. In response to the determination unit having determined that the vehicle is in the deceleration state, the display control unit is configured to display on the display unit the information including a display moving from an upper side to a lower side along a vertical direction of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2019-189435 filed on Oct. 16, 2019, which is incorporated herein byreference in its entirety including the specification, drawings andabstract.

BACKGROUND 1. Technical Field

The present disclosure relates to a display device and display methodfor a display device.

2. Description of Related Art

U.S. Pat. No. 9,196,164 discloses a vehicle that travels autonomously.The vehicle includes a display unit that displays information to theoutside of the vehicle. The display unit displays a stop road sign tonotify that pedestrians are not permitted to pass before the vehicle.The display unit displays a message indicating that it is safe to crossin written and graphic form to notify pedestrians that it is safe tocross in front of the vehicle.

SUMMARY

In the device disclosed in U.S. Pat. No. 9,196,164, pedestrians or thedrivers of other vehicles (hereinafter referred to as others) may havedifficulty in recognizing the intentions of the vehicle. For example,when the vehicle presents the stop road sign, the others may be confusedwhether the sign notifies that they need to stop or notifies that thevehicle will stop. Furthermore, since road signs and writing are countryor area specific, the others may be unable to understand the intentionsof the road signs or writing that they recognized.

The present disclosure provides a display device that allows smoothcommunication with others.

A first aspect of the present disclosure is a display device provided ina vehicle that travels autonomously. The display device includes adisplay unit, a determination unit, and a display control unit. Thedisplay unit is configured to display information to the outside of thevehicle. The determination unit is configured to determine whether atravel state of the vehicle is any one of a deceleration state, a stopstate, and a start state, based on the detection result of an internalsensor of the vehicle. The display control unit is configured to displayon the display unit the information corresponding to each of thedeceleration state, the stop state, and the start state, based on thedetermination result of the determination unit. In response to thedetermination unit having determined that the vehicle is in thedeceleration state, the display control unit is configured to display onthe display unit the information including optical presentation movingfrom an upper side to a lower side along a vertical direction of thevehicle.

In the display device, whether the travel state of the vehicle is in anyone of a deceleration state, a stop state, and a start state isdetermined by the determination unit. Based on the determination resultof the determination unit, the information corresponding to each of thedeceleration state, the stop state, and the start state is displayed onthe display unit by the display control unit. Thus, the display devicecan display the state of the vehicle to the outside of the vehicle.Then, in response to the determination unit having determined that thevehicle is in the deceleration state, the information including opticalpresentation moving from an upper side to a lower side along a verticaldirection of the vehicle is displayed on the display unit by the displaycontrol unit. Thus, the deceleration state of the vehicle is expressedby using optical presentation moving from the upper side to the lowerside along the vertical direction of the vehicle. Since such opticalpresentation gives others an image of energy conversion, a largemajority of others can understand the deceleration state of the vehicleas compared with the country or area specific road signs or writing.

Accordingly, the display control unit can provide smooth communicationwith others.

In one embodiment, the display control unit may display on the displayunit the information including optical presentation, when speed of thevehicle is equal to a prescribed value or less. When communicationbetween the vehicle and a pedestrian is taken into consideration, anopportunity to communicate increases as the speed of the vehicle and thepedestrian become closer. The display device can start and endcommunication with a pedestrian with appropriate timing by limiting acondition of displaying the optical presentation to the time when thespeed of the vehicle is equal to a prescribed value or less.

A second aspect of the present disclosure is a display method for adisplay device. The display device is provided in a vehicle that travelsautonomously and the display device includes a display unit thatdisplays information to an outside of the vehicle. The method includes,determining whether a travel state of the vehicle is any one of adeceleration state, a stop state, and a start state, based on adetection result of an internal sensor of the vehicle; and displayingthe information corresponding to each of the deceleration state, thestop state, and the start state, based on a determination result. Inresponse to the determination that the vehicle is in the decelerationstate, displaying on the display unit the information including adisplay moving from an upper side to a lower side along a verticaldirection of the vehicle.

In the second aspect, the method may displaying on the display unit theinformation including the display, when speed of the vehicle is equal toa prescribed value or less.

According to various aspects and embodiments of the present disclosure,smooth communication with others can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the disclosure will be described below withreference to the accompanying drawings, in which like numerals denotelike elements, and wherein:

FIG. 1 is a functional block diagram of an example of a vehicleincluding a display device according to a first embodiment;

FIG. 2A shows an example of a position of mounting a display unit on thevehicle;

FIG. 2B shows an example of the position of mounting the display unit onthe vehicle;

FIG. 2C shows an example of the position of mounting the display unit onthe vehicle;

FIG. 3 illustrates an example of display timing;

FIG. 4 is a flowchart showing an example of the operation of the displaydevice;

FIG. 5 is a table illustrating an example of the details of displayaspects;

FIG. 6A illustrates an example of deceleration display;

FIG. 6B illustrates an example of the deceleration display;

FIG. 6C illustrates an example of the deceleration display;

FIG. 6D illustrates an example of the deceleration display;

FIG. 7A is a table illustrating an example of the details of the displayaspects;

FIG. 7B is a table illustrating an example of the details of the displayaspects;

FIG. 7C is a table illustrating an example of the details of the displayaspects;

FIG. 7D is a table illustrating an example of the details of the displayaspects;

FIG. 8 is a functional block diagram of an example of the vehicleincluding a display device according to a second embodiment;

FIG. 9 is a flowchart showing an example of the operation of the displaydevice; and

FIG. 10 is a flowchart showing an example of a notification process.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, exemplary embodiments will be described with reference tothe drawings. In the following description, like or correspondingcomponent members are designated by like reference numerals to omitredundant explanation.

First Embodiment

Configuration of Vehicle and Display Device

FIG. 1 is a functional block diagram of an example of a vehicle 2including a display device 1 according to a first embodiment. As shownin FIG. 1, the display device 1 is mounted on the vehicle 2, such as apassenger car, to notify information to peripheral vehicles presentaround the vehicle 2. In one example, the vehicle 2 is a vehicle thattravels autonomously. Autonomous driving is vehicle control forperforming autonomous travel of the vehicle 2 toward a destination setin advance. The destination may be set by an occupant, such as a driver,or may automatically be set by the vehicle 2. In autonomous driving, thevehicle 2 travels autonomously without the necessity of the driverperforming driving operation.

The vehicle 2 includes an external sensor 3, a GPS receiver 4, aninternal sensor 5, a map database 6, a navigation system 7, anautonomous driving ECU 8, and an actuator 9.

The external sensor 3 is a detector that detects the situation aroundthe vehicle 2. The external sensor 3 detects the position of an objectahead of a roadway on which the vehicle 2 travels. The external sensor 3includes at least one of a camera and a radar sensor.

The camera is an imaging device that images an external situation of thevehicle 2. For example, the camera is provided on the back side of awindshield of the vehicle 2. The camera acquires imaging informationregarding the external situation of the vehicle 2. The camera may be amonocular camera or may be a stereoscopic camera. The stereoscopiccamera has two imaging units arranged to reproduce a binoculardisparity. Imaging information of the stereoscopic camera includesdepth-directional information.

The radar sensor is a detector that detects an object around the vehicle2 with use of electric waves (such as millimeter waves) or light.Examples of the radar sensor include a millimeter-wave radar or a laserimaging detection and ranging (LIDAR). The radar sensor detects anobject by transmitting an electric wave or light to the periphery of thevehicle 2 and receiving the electric wave or light reflected by theobject.

The GPS receiver 4 receives signals from three or more GPS satellites toacquire location information indicating the location of the vehicle 2.For example, the location information includes latitude and longitude.The GPS receiver 4 may be replaced with other devices that can identifythe latitude and longitude indicating where the vehicle 2 is present.

The internal sensor 5 is a detector that detects a travel state of thevehicle 2. The internal sensor 5 includes a vehicle speed sensor, anacceleration sensor, and a yaw rate sensor. The vehicle speed sensor isa detector that detects the speed of the vehicle 2. Used as the vehiclespeed sensor is a wheel speed sensor provided in a wheel of the vehicle2 or in a drive shaft that integrally rotates with the wheel, or thelike, to detect rotation speed of the wheel.

The acceleration sensor is a detector that detects acceleration of thevehicle 2. The acceleration sensor may include a longitudinalacceleration sensor that detects acceleration in a longitudinaldirection of the vehicle 2 and a lateral acceleration sensor thatdetects acceleration of the vehicle 2. The yaw rate sensor is a detectorthat detects a yaw rate (rotational angular speed) around a verticalaxis of the center of gravity of the vehicle 2. As the yaw rate sensor,a gyro sensor may be used, for example.

The map database 6 is a storage device that stores map information. Themap database 6 is stored in a hard disk drive (HDD) mounted in thevehicle 2, for example. The map database 6 includes information onstatic objects, traffic rules, and the positions of traffic signals, asmap information. Examples of the static objects include road surfacepaints (including lane boundary lines, such as white lines and yellowlines) and structures (such as curbstones, poles, electric poles,buildings, indicators, and trees). Some of the map information includedin the map database 6 may be stored in a storage device different fromthe HDD that stores the map database 6. Some or all of the mapinformation included in the map database 6 may be stored in a storagedevice other than the storage device provided in the vehicle 2.

The navigation system 7 guides the driver of the vehicle 2 to thedestination set in advance. The navigation system 7 recognizes travelroads and travel lanes for the vehicle 2 to travel, based on thelocation of the vehicle 2 measured by the GPS receiver 4 and on the mapinformation in the map database 6. The navigation system 7 calculates atarget route from the location of the vehicle 2 to the destination, andguides the driver along the target route with a human machine interface(HMI).

The actuator 9 is a device that executes travel control of the vehicle2. The actuator 9 includes at least an engine actuator, a brakeactuator, and a steering actuator. The engine actuator changes theamount of air supplied to the engine (for example, changes a throttleopening angle) in response to a control signal from the autonomousdriving ECU 8 so as to control drive power of the vehicle 2. The engineactuator controls drive power of a motor as a driving power source, whenthe vehicle 2 is a hybrid vehicle or an electric vehicle.

The autonomous driving ECU 8 controls the vehicle 2. An ECU is anelectronic control unit including a central processing unit (CPU), aread only memory (ROM), a random access memory (RAM), and a controllerarea network (CAN) communication circuit. For example, the autonomousdriving ECU 8 is connected to a network that communicates with use ofthe CAN communication circuit, and is communicably connected with theabove-described component members of the vehicle 2. For example, theautonomous driving ECU 8 implements autonomous driving functions byoperating the CAN communication circuit to allow data input and output,storing the data in the RAM, loading the programs stored in the ROM tothe RAM, and executing the programs loaded to the RAM, based on signalsoutput from the CPU. The autonomous driving ECU 8 may be configured witha plurality of electronic control units.

In one example, the autonomous driving ECU 8 recognizes objects(including the position of the object) around the vehicle 2, based on atleast one of the detection result of the external sensor 3 and the mapdatabase 6. The objects include unmovable static objects, such aselectric poles, guardrails, trees, and buildings, as well as dynamicobjects, such as pedestrians, bicycles, and other vehicles. For example,the autonomous driving ECU 8 performs object recognition whenever theautonomous driving ECU 8 acquires the detection result from the externalsensor 3. The autonomous driving ECU 8 may recognize the objects byother well-known methods.

In one example, the autonomous driving ECU 8 detects dynamic objects,among the recognized objects, by using the information on the staticobjects included in the map database 6. The autonomous driving ECU 8 maydetect the dynamic objects by other well-known methods.

The autonomous driving ECU 8 applies a filter such as a Kalman filter ora particle filter to the detected dynamic objects, and detects movingamounts of the dynamic objects at the time. The moving amount includesthe moving directions and moving speeds of the dynamic objects. Themoving amounts may include rotation speeds of the dynamic objects. Theautonomous driving ECU 8 may estimate error of the moving amounts.

The autonomous driving ECU 8 recognizes the travel state of the vehicle2, based on the detection result (for example, vehicle speed informationof the vehicle speed sensor, acceleration information of theacceleration sensor, yaw rate information of the yaw rate sensor, etc.)of the internal sensor 5. For example, the travel state of the vehicle 2includes the vehicle speed, the acceleration, and the yaw rate.

The autonomous driving ECU 8 recognizes the boundary lines of the lanein which the vehicle 2 travels, based on the detection result of theexternal sensor 3.

The autonomous driving ECU 8 generates a route of the vehicle 2, basedon the detection result of the external sensor 3, the map database 6,the recognized location of the vehicle 2 on the map, the information onthe recognized objects (including lane boundary lines), the recognizedtravel state of the vehicle 2, and the like. At the time, the autonomousdriving ECU 8 generates the route of the vehicle 2 based on theassumption of the behaviors of the objects around the vehicle 2.Examples of the assumption of the behaviors of the objects may includean assumption that all the objects around the vehicle 2 are staticobjects, an assumption that the dynamic objects move independently, andan assumption that the dynamic objects move while interacting with atleast one of other objects and the vehicle 2.

The autonomous driving ECU 8 generates a plurality of route candidatesof the vehicle 2 by using a plurality of assumptions. The routecandidates include at least one route for the vehicle 2 to travel whileavoiding objects. The autonomous driving ECU 8 selects one route basedon the reliability of each route candidate, or the like.

The autonomous driving ECU 8 generates a travel plan corresponding tothe selected route. The autonomous driving ECU 8 generates the travelplan corresponding to the route of the vehicle 2, based on the detectionresult of the external sensor 3 and the map database 6. The autonomousdriving ECU 8 generates the travel plan within a range that the vehiclespeed does not exceed the speed limits of the travel lanes, by using thespeed limits stored in the map database 6. The autonomous driving ECU 8also generates the travel plan such that the vehicle 2 travels so as notto exceed prescribed upper speed limits.

The autonomous driving ECU 8 outputs the travel plan to be generatedsuch that the route of the vehicle 2 has a plurality of pairs of twoelements: a target position p in a coordinate system fixed to thevehicle 2 and a speed V in each of the target points, i.e., a pluralityof configuration coordinates (p, V). Here, each target position p has atleast the positions of an x-coordinate and a y-coordinate in thecoordinate system fixed to the vehicle 2, or the information equivalentthereto. The travel plan is not particularly limited as long as thebehavior of the vehicle 2 is defined. For example, the travel plan mayinclude target time t instead of the speed V, or may additionallyinclude the target time t and the direction of the vehicle 2 at thetarget time t. The travel plan may be data indicating transition of thevehicle speed, acceleration-deceleration speed, and steering torque ofthe vehicle 2 at the time when the vehicle 2 travels on the route. Thetravel plan may include a speed pattern, an acceleration-decelerationspeed pattern, and a steering pattern of the vehicle 2.

The autonomous driving ECU 8 autonomously controls travel of the vehicle2 based on the generated travel plan. The autonomous driving ECU 8outputs control signals corresponding to the travel plan to the actuator9. Accordingly, the autonomous driving ECU 8 controls the travel of thevehicle 2 such that the vehicle 2 travels autonomously along with thetravel plan.

The display device 1 includes a display ECU 10 and a display unit 13.The display ECU 10 is an electronic control unit that controls displayof information. The display ECU 10 may be configured with a plurality ofECUs, or may be included in the autonomous driving ECU 8. The displayunit 13 is a device provided in the vehicle 2 to notify information tothe outside of the vehicle. The display unit 13 is connected to thedisplay ECU 10 to notify information based on the output signals of thedisplay ECU 10.

The information notified by the display unit 13 is information to benotified to the pedestrians who are present around the vehicle 2 or thedrivers of peripheral vehicles. In one example, the peripheral vehiclesare vehicles present in the range that is recognizable by the externalsensor 3 of the vehicle 2. The peripheral vehicles may be other thanvehicles. For example, the peripheral vehicles may include mobileobjects, such as motorcycles and bicycles. The information to benotified is the result obtained by using the internal sensor 5, such asspeed information or acceleration information relating to the vehicle 2.The information to be notified may be the result obtained by using theexternal sensor 3, such as detection information or recognitioninformation relating to the vehicle 2. Alternatively, the informationmay be the information obtained from the autonomous driving ECU 8, suchas a present action or a future action of the vehicle 2. Although theinformation to be notified is the state of the vehicle obtained by usingthe internal sensor 5 in the following description, the information isnot limited to this.

The display unit 13 is a display device in one example. The display unit13 is disposed in a position that is visually recognizable from thefront, rear or lateral sides of the vehicle 2. FIGS. 2A to 2C showexamples of the position of the display unit 13 mounted on the vehicle.As shown in FIG. 2A, a front display device 13 g is provided as thedisplay unit 13 in a grill portion of the front surface of the vehicle2. As shown in FIG. 2B, a rear display device 13 h is provided as thedisplay unit 13 on the rear surface of the vehicle 2. Furthermore, asshown in FIG. 2C, a side display device 13 j is provided as the displayunit 13 on a side surface of the vehicle 2. The display unit 13 is notlimited to the examples shown in FIG. 2A to 2C. Two or more displayunits 13 may be provided in the grill portion of the front surface ofthe vehicle 2, or the display devices may be provided on the rearsurface and side surface of the vehicle 2.

The display ECU 10 includes a determination unit 11, and a displaycontrol unit 12.

The determination unit 11 determines whether the travel state of thevehicle 2 is any one of a deceleration state, a stop state, and a startstate, based on the detection result of the internal sensor 5 of thevehicle 2. The determination unit 11 determines the travel state of thevehicle 2 using a speed change or the absolute value of a speedpredetermined for every travel state. For example, when the speed changehas a tendency to decrease, the determination unit 11 determines thatthe travel state of the vehicle 2 is the deceleration state.

For example, when the absolute value of the speed is close to zero andwhen there is no speed change, the determination unit 11 determines thatthe travel state of the vehicle 2 is the stop state. For example, whenthe absolute value of the speed is close to zero but the speed changehas a tendency to increase, the determination unit 11 determines thatthe travel state of the vehicle 2 is the start state.

The display control unit 12 displays on the display unit 13 theinformation corresponding to each of the deceleration state, the stopstate, and the start state based on the determination result of thedetermination unit 11. The information corresponding to the decelerationstate, the information corresponding to the stop state, and theinformation corresponding to the start state are different from eachother and set in advance. The details of the display will be describedlater.

Example of Display Timing

FIG. 3 illustrates an example of display timing. An example where thevehicle 2 gives way to a pedestrian H1 will be described with referenceto FIG. 3. During traveling, the display control unit 12 turns off (OFF)the display unit 13 of the vehicle 2. As shown in FIG. 3, it is assumedthat the autonomous driving ECU 8 recognizes the pedestrian H1 ahead ofthe vehicle 2 at time t1. The autonomous driving ECU 8 starts todecelerate the vehicle 2 at time t2 in order to give way to thepedestrian H1. At the time, the display control unit 12 changes adeceleration display from OFF to ON. Accordingly, the display unit 13starts the deceleration display at time t2. The deceleration display isa display that indicates that the vehicle 2 is decelerating. Next, attime t3, the autonomous driving ECU 8 stops the vehicle 2 before thepedestrian H1. At the time, the display control unit 12 changes thedeceleration display from ON to OFF, and changes a stop display from OFFto ON. Accordingly, at time t3, the display unit 13 ends thedeceleration display and starts a stop display. The stop display is adisplay that indicates that the vehicle 2 is in a stopped state. Next,at time t4, the autonomous driving ECU 8 confirms that the pedestrian H1has finished crossing, and starts the vehicle 2. At the time, thedisplay control unit 12 changes the stop display from ON to OFF, andchanges a start display from OFF to ON. Accordingly, at time t4, thedisplay unit 13 ends the stop display and starts the start display.After the vehicle 2 is started, the display control unit 12 changes thestart display from ON to OFF at the timing when the vehicle speedbecomes a prescribed speed or more.

Operation of Display Device

FIG. 4 is a flowchart showing an example of the operation of the displaydevice. The flowchart shown in FIG. 4 is executed by the display ECU 10of the display device 1. The display ECU 10 starts the process when, forexample, a display start button is turned on by operation of a driver.

As shown in FIG. 4, the determination unit 11 of the display ECU 10acquires the speed of the vehicle 2 detected by the internal sensor 5 asa vehicle speed acquisition process (S10). Next, as a statedetermination process (S12), the determination unit 11 determineswhether the travel state of the vehicle 2 is any one of the decelerationstate, the stop state, and the start state, based on the speed obtainedin the vehicle speed acquisition process (S10).

Next, as a display process (S14), the display control unit 12 of thedisplay

ECU 10 displays the information corresponding to each of thedeceleration state, the stop state, and the start state on the displayunit based on the determination result of the state determinationprocess (S12). When the display process (S14) is ended, the flowchartshown in FIG. 4 is ended. After the flowchart is ended, the flowchartshown in FIG. 4 is conducted from the beginning until a display endcondition is satisfied. The display end condition is satisfied when, forexample, a display end button is turned on by operation of the driver.

Details of Display Aspects

The details of the display performed by the display unit 13 in thedisplay process (S14) will be described with reference to FIGS. 5 to 7D.FIG. 5 is a table illustrating an example of the details of displayaspects. FIGS. 6A to 6D illustrate examples of the deceleration display.FIGS. 7A to 7D are tables illustrating examples of the details of thedisplay aspects.

As shown in FIG. 5, the travel states of the vehicle 2 and displayexpressions are associated in advance. The display control unit 12controls display of the display unit 13 based on the correspondenceshown in FIG. 5. The display control unit 12 provides an opticalpresentation using an optical graphic (hereinafter, also referred to asan object), for example. The optical presentation is to move thedisplayed optical graphic by changing light emission in time series.

The display control unit 12 changes vertical movement of the opticalgraphic, as vertical expression, in accordance with the travel state ofthe vehicle 2. For example, when the travel state of the vehicle 2 isthe deceleration state, the display control unit 12 provides the opticalpresentation such that the object flows from an upper side to a lowerside. For example, when the travel state of the vehicle 2 is the stopstate, the display control unit 12 provides the optical presentationsuch that the optical graphic slowly moves up and down with stagnation(stagnation expression). For example, when the travel state of thevehicle 2 is the start state, the display control unit 12 provides theoptical presentation such that the object flows from the lower side tothe upper side.

A detailed description is given of an example of the decelerationdisplay in the vertical expression. FIGS. 6A to 6D are provided in atime series order. As shown in FIG. 6A, the display control unit 12first displays an object OB1 that is an optical line on an upper portionof a display area of the display unit 13. Then, as shown in FIGS. 6B to6D, the display control unit 12 shifts the object OB1 downward with alapse of time. When the object OB1 passes a lower end of the displayarea of the display unit 13, the display control unit 12 displays a nextobject OB1 on the upper portion of the display area of the display unit13. Accordingly, the optical presentation is provided such that theobject OB1 continuously moves from the upper side to the lower side. Thedisplay control unit 12 may display the next object OB1 on the upperportion of the display area of the display unit 13, before the firstobject OB1 reaches the lower end of the display area of the display unit13. In this case, the optical presentation is provided such that aplurality of objects OB1 flow from the upper side to the lower side.With the aspect of the object OB1 flowing from the upper side to thelower side, an image of energy convergence, i.e., deceleration, can beexpressed.

FIGS. 7A to 7C illustrate examples of deceleration display, stopdisplay, and start display in the vertical expression, respectively.FIG. 7A is an example of the deceleration display in the verticalexpression. As described above, the presentation of the object OB1flowing from the upper side to the lower side is provided as shown by anarrow in the drawing. FIG. 7B is an example of the stop display in thevertical expression. An object OB2 shown in FIG. 7B slowly operates upand down in a low period in the vicinity of the center of the displayarea of the display unit 13 as shown by an arrow in the drawing. Suchstagnation expression can express the stop of the vehicle 2. FIG. 7C isan example of the start display in the vertical expression. An objectOB3 shown in FIG. 7C moves in the direction opposite to the object OB1,i.e., flows from the lower side to the upper side as shown by an arrowin the drawing. With the presentation of the object OB3 flowing from thelower side to the upper side, an image of energy divergence, i.e.,start, can be expressed.

The above-described optical presentations are merely examples, and thedisplay unit 13 can display various graphics. For example, as the stopdisplay, a pedestrian and a pedestrian crossing as shown in FIG. 7D canalso be illustrated.

The display control unit 12 can also provide horizontal expression likethe vertical expression described above. As the horizontal expression,the display control unit 12 changes a horizontal movement of an opticalgraphic in accordance with the travel state of the vehicle 2. Forexample, when the travel state of the vehicle 2 is the decelerationstate, the display control unit 12 provides the optical presentationsuch that an object flows from outside to inside. This expresses animage of energy convergence, i.e., deceleration. For example, when thetravel state of the vehicle 2 is the stop state, the display controlunit 12 provides the optical presentation such that the optical graphicslowly moves in the horizontal direction with stagnation (stagnationexpression). This expresses the stop of the vehicle. For example, whenthe travel state of the vehicle 2 is the start state, the displaycontrol unit 12 provides the optical presentation such that the objectflows from the inside to the outside. This expresses an image of energydivergence, i.e., start.

The display control unit 12 can provide a front-rear expression like thevertical expression described before. As the front-rear expression, thedisplay control unit 12 changes a front-rear movement of the opticalgraphic in accordance with the travel state of the vehicle 2. Forexample, when the travel state of the vehicle 2 is the decelerationstate, the display control unit 12 provides the optical presentationsuch the object flows from the front side to the rear side. Accordingly,deceleration can be expressed by synchronizing the motion of the vehiclewith the motion of light. For example, when the travel state of thevehicle 2 is the stop state, the display control unit 12 provides theoptical presentation such that the optical graphic slowly moves in thefront-rear direction with stagnation (stagnation expression). Thisexpresses the stop of the vehicle. For example, when the travel state ofthe vehicle 2 is the start state, the display control unit 12 providesthe optical presentation such that the object flows from the rear sideto the front side. Accordingly, the start can be expressed bysynchronizing the motion of the vehicle with the motion of light.

The display control unit 12 can change the area of the object as in thecase of the vertical expression described above. As the area change, thedisplay control unit 12 changes the area of the optical graphic inaccordance with the travel state of the vehicle 2.

For example, when the travel state of the vehicle 2 is the decelerationstate, the display control unit 12 provides the optical presentationsuch that the area of the object becomes narrower (convergingexpression). This expresses an image of energy convergence, i.e.,deceleration. For example, when the travel state of the vehicle 2 is thestop state, the display control unit 12 provides the opticalpresentation such that the area of the object becomes wider or narrower(stagnation expression). This expresses the stop of the vehicle. Forexample, when the travel state of the vehicle 2 is the start state, thedisplay control unit 12 provides the optical presentation such that thearea of the object becomes wider (diverging change). This expresses animage of energy divergence, i.e., start.

As other presentation effects, the display control unit 12 may changethe color of the optical graphic in accordance with the travel state ofthe vehicle 2. For example, when the travel state of the vehicle 2 isthe deceleration state, the display control unit 12 colors the objectorange. This expresses that the vehicle 2 is coming closer, and otherscan be alerted. For example, when the travel state of the vehicle 2 isthe stop state, the display control unit 12 colors the object green.This expresses the state where the vehicle 2 is stopped and stable togive the others a safe impression. For example, when the travel state ofthe vehicle 2 is the start state, the display control unit 12 colors theobject white. This expresses that the vehicle 2 begins to move, andothers can be alerted.

As other presentation effects, the display control unit 12 may changethe speed of the motion of the optical graphic in accordance with thetravel state of the vehicle 2. For example, when the travel state of thevehicle 2 is the deceleration state, the display control unit 12 flashesthe object in a first period (long period). Such gradual flashing canexpress deceleration. For example, when the travel state of the vehicle2 is the stop state, the display control unit 12 lights the object. Thisexpresses that the vehicle is in a stopped state. For example, when thetravel state of the vehicle 2 is the start state, the display controlunit 12 flashes the object in a second period (short period) that isshorter than the first period. This expresses the start state of thevehicle with a slight alertness.

As other presentation effects, the display control unit 12 may changethe tone of light in accordance with the travel state of the vehicle 2.The display control unit 12 sets the luminance to three levels includinglarge, middle, and small. For example, when the travel state of thevehicle 2 is the deceleration state, the display control unit 12 may setthe luminance of the object to middle. Thus, the luminance at the middlelevel can express gradual deceleration. For example, when the travelstate of the vehicle 2 is the stop state, the display control unit 12sets the luminance of the object to small. This expresses that thevehicle is in the stopped state. For example, when the travel state ofthe vehicle 2 is the start state, the display control unit 12 sets theluminance of the object to large. This expresses the start state of thevehicle with a slight alertness.

Summary of First Embodiment

In the display device 1 according to the first embodiment, whether thetravel state of the vehicle 2 is in any one of a deceleration state, astop state, and a start state is determined by the determination unit11. Based on the determination result of the determination unit 11, theinformation corresponding to each of the deceleration state, the stopstate, and the start state is displayed on the display unit 13 by thedisplay control unit 12. Thus, the display device 1 can display thestate of the vehicle 2 to the outside of the vehicle. Then, in responseto the determination unit 11 having determined that the vehicle 2 is inthe deceleration state, the information including optical presentationmoving from an upper side to a lower side along a vertical direction ofthe vehicle 2 is displayed on the display unit 13 by the display controlunit 12. Thus, the deceleration state of the vehicle 2 is expressed byoptical presentation moving from the upper side to the lower side alongthe vertical direction of the vehicle 2. Since such optical presentationgives others an image of energy conversion, a large majority of otherscan understand the deceleration state of the vehicle as compared withthe country or area specific road signs or writing. Accordingly, thedisplay control unit can provide smooth communication with others.Moreover, optical presentation is not limited by the shape or size ofthe display area of the display unit 13. Accordingly, the display device1 can provide notification that is not limited by the shape or size ofthe display area of the display unit 13.

Second Embodiment

A display device 1A according to the second embodiment is similar to thedisplay device 1 according to the first embodiment except for the pointthat the display ECU in the second embodiment includes a notificationdetermination unit 111 and the point that the function of the displaycontrol unit 12 is partially different. Hereinafter, description ismainly given of the difference from the first embodiment, and thedescription of the similar parts is not redundantly provided.

Configuration of Vehicle and Display Device

FIG. 8 is a functional block diagram of an example of the vehicleincluding a display device according to the second embodiment. A vehicle2A is similar to the vehicle 2 except for the point that a displaydevice 1A is included. The display device 1A includes a display ECU 10Aand a display unit 13. The display ECU 10A includes a notificationdetermination unit 111, a determination unit 11, and a display controlunit 12. The notification determination unit 111 determines whether ornot a notification target candidate is present in the periphery of thevehicle 2A. The notification determination unit 111 acquires recognitioninformation regarding the objects around the vehicle 2A (pedestrians,bicycles, other vehicles, etc.) from an autonomous driving ECU 8. Therecognition information includes a type, a position, a speed, a movingdirection, face orientation, or the like, of the objects. When therecognition information regarding the objects is acquired, thenotification determination unit 111 determines that the notificationtarget candidate is present. When the recognition information regardingthe objects is not acquired, the notification determination unit 111determines that the notification target candidate is not present. Whenthe notification target candidate is present, the notificationdetermination unit 111 determines whether or not there is an opportunityof communication with the notification target candidate, based on therecognition information regarding the objects. As an example of theopportunity of communication, an aid for crossing a road for apedestrian will be described. When a scheduled route of the notificationtarget candidate intersects a scheduled route of the vehicle 2A, thenotification determination unit 111 determines that there is anopportunity of communication. The scheduled route of the notificationtarget candidate is determined based on a current moving direction, faceorientation, the presence or absence of a pedestrian crossing, and thelike. When the scheduled route of the notification target candidate doesnot cross the scheduled route of the vehicle 2A, the notificationdetermination unit 111 determines that there is no opportunity ofcommunication. The notification determination unit 111 sets thenotification target candidate, determined to have an opportunity ofcommunication, as a notification target. The notification determinationunit 111 may perform the process by using the result of the externalsensor 3, without using the recognition result of the autonomous drivingECU 8.

The display control unit 12 determines whether or not the speed of thevehicle 2A is equal to a prescribed value or less, based on thedetection result of the internal sensor 5. The prescribed value is apreset speed that is a threshold for determining the necessity ofnotification. The prescribed value is 40 km/h in one example. When thespeed of the vehicle 2A is equal to the prescribed value or less, thedisplay control unit 12 controls the display unit 13. The display unit13 displays to the outside of the vehicle. The display control unit 12does not control the display unit 13, when the speed of the vehicle 2Aexceeds the prescribed value. The display unit 13 does not display tothe outside of the vehicle.

The display control unit 12 controls the display unit 13, when thenotification determination unit 111 determines that there is anotification candidate. The display unit 13 displays to the outside thevehicle. The display control unit 12 does not control the display unit13, when the notification determination unit 111 determines that thereis no notification candidate. The display unit 13 does not display tothe outside of the vehicle. Other configurational aspects of the displaydevice 1A are similar to those of the display device 1.

Operation of Display Device

FIG. 9 is a flowchart showing an example of the operation of the displaydevice. The flowchart shown in FIG. 9 is executed by the display ECU 10Aof the display device 1A. The display ECU 10A starts the process when,for example, a display start button is turned on by operation of adriver.

As shown in FIG. 9, the determination unit 11 of the display ECU 10Aacquires the speed of the vehicle 2A detected by the internal sensor 5as a vehicle speed acquisition process (S20). Next, as a vehicle speeddetermination process (S22), the display control unit 12 of the displayECU 10A determines whether or not the speed of the vehicle 2A acquiredin the vehicle speed acquisition process (S20) is equal to a prescribedvalue or less.

When the display control unit 12 determines that the speed of thevehicle 2A is equal to the prescribed value or less (S22: YES), thenotification determination unit 111 of the display ECU 10A determineswhether or not a notification target candidate is detected as acandidate determination process (S24). When the result of recognizing anobject by the autonomous driving ECU 8 is acquired, the notificationdetermination unit 111 determines that there is a notification targetcandidate. When the result of recognizing an object by the autonomousdriving ECU 8 is not acquired, the notification determination unit 111determines that there is no notification target candidate.

When determining that notification target candidate is detected (S24 :YES), the notification determination unit 111 determines, as a targetdetermination process (S26), whether there is an opportunity ofcommunication with the notification target candidate based on therecognition information regarding the notification target candidate. Thenotification determination unit 111 determines the notification targetcandidate with the opportunity of communication as a notificationtarget. The notification determination unit 111 determines thenotification target candidate without the opportunity of communicationas a non-notification target.

When the notification determination unit 111 determines that there is anotification target (S26: YES), the display control unit 12 of thedisplay ECU 10A displays the information on the display unit 13 as anotification process (S28). The details of the notification process(S28) will be described later.

When the notification process (S28) is ended, the flowchart shown inFIG. 9 is ended. When the notification determination unit 111 determinesthat the speed of the vehicle 2A is not equal to the prescribed value orless (S22: NO), when the notification determination unit 111 determinesthat the notification target candidate is not detected (S24: NO), andwhen the notification determination unit 111 determines that there is nonotification target (S26: NO), the flowchart shown in FIG. 9 is endedwithout execution of the notification. After the flowchart is ended, theflowchart shown in FIG. 9 is conducted from the beginning until anotification end condition is satisfied. The notification end conditionis satisfied when, for example, a display end button is turned on byoperation of the driver. Details of Notification Process

FIG. 10 is a flowchart showing an example of the notification process.The flowchart shown in FIG. 10 shows the detail of the notificationprocess (S28) of FIG. 9.

First, the determination unit 11 of the display ECU 10A determineswhether the vehicle 2A is starting as a travel state determinationprocess (S30). The determination unit 11 determines whether or not thevehicle 2A is starting based on the speed obtained in the vehicle speedacquisition process (S20). When the determination unit 11 determinesthat the vehicle 2A is starting (S30: YES), the display control unit 12displays a start display on the display unit 13 as a start displayprocess (S32).

The determination unit 11 may determine whether the vehicle 2A isscheduled to start as the travel state determination process (S30). Thedetermination unit 11 may determine that the vehicle 2A is scheduled tostart, when receiving a signal indicating that the vehicle 2A isscheduled to start after a prescribed time from the autonomous drivingECU 8. When the determination unit 11 determines that the vehicle 2A isscheduled to start, the display control unit 12 may execute the startdisplay process (S32).

When the determination unit 11 determines that the vehicle 2A is notstarting (S30: NO), the display control unit 12 determines whether ornot the vehicle 2A is decelerating as a travel state determinationprocess (S34). The determination unit 11 determines whether or not thevehicle 2A is decelerating based on the speed obtained in the vehiclespeed acquisition process (S20). When the display control unit 12determines that the vehicle 2A is decelerating (S34: YES), the displaycontrol unit 12 displays a deceleration display on the display unit 13as a deceleration display process (S36).

When the determination unit 11 determines that the vehicle 2A is notdecelerating (S34: NO), the display control unit 12 determines whetheror not the vehicle 2A is in a stopped state as a travel statedetermination process (S38). The determination unit 11 determineswhether or not the vehicle 2A is in the stopped state based on the speedobtained in the vehicle speed acquisition process (S20). When thedisplay control unit 12 determines that the vehicle 2A is in the stoppedstate (S38: YES), the display control unit 12 displays a stop display onthe display unit 13 as a stop display process (S40).

When the display control unit 12 performs the start display process(S32), the deceleration display process (S36), and the stop displayprocess (S40), and when the display control unit 12 determines that thevehicle 2A is not in the stopped state (S38: NO), the flowchart shown inFIG. 10 is ended. After the flowchart is ended, the process returns tothe notification process (S28) of FIG. 9.

Summary of Second Embodiment

The display device 1A according to the second embodiment demonstratesthe same effects as the display device 1 according to the firstembodiment. Furthermore, since the display device 1A performsnotification when the speed of the vehicle 2A is equal to the prescribedvalue or less, it is possible to start and end communication with apedestrian with appropriate timing.

Although various exemplary embodiments have been described in theforegoing, the present disclosure may be subject to various omission,replacement, and modification, without being limited to the exemplaryembodiments.

For example, the display unit 13 does not need to be provided outsidethe vehicle 2. As long as information can be notified to the outside ofthe vehicle, the display unit 13 may be provided inside the vehicle,such as inside the windshield glass. Without being limited to thedisplay device, the display unit 13 may be any light emitting devices,such as a lamp. The display device 1 may further display deceleration,stop, and start in writing when a display device is adopted as thedisplay unit 13. The display unit 13 may be a projector that projectsoptical presentation on a road surface.

Since some functions of the display devices 1, 1A are overlapped withthe functions of the autonomous driving ECU 8, the display ECU 10 may beconfigured to acquire the result of calculation performed by theautonomous driving ECU 8.

The vehicle speed determination process (S22) of FIG. 9 may be executedany time, as long as after the start of the process of FIG. 9 and beforethe notification process (S28).

What is claimed is:
 1. A display device provided in a vehicle thattravels autonomously, comprising: a display unit configured to displayinformation to an outside of the vehicle; a determination unitconfigured to determine whether a travel state of the vehicle is any oneof a deceleration state, a stop state, and a start state, based on adetection result of an internal sensor of the vehicle; and a displaycontrol unit configured to display on the display unit the informationcorresponding to each of the deceleration state, the stop state, and thestart state, based on a determination result of the determination unit,wherein: in response to the determination unit having determined thatthe vehicle is in the deceleration state, the display control unit isconfigured to display on the display unit the information including adisplay moving from an upper side to a lower side along a verticaldirection of the vehicle.
 2. The display device according to claim 1,wherein the display control unit displays on the display unit theinformation including the display, when speed of the vehicle is equal toa prescribed value or less.
 3. A display method for a display device,the display device being provided in a vehicle that travels autonomouslyand the display device including a display unit that displaysinformation to an outside of the vehicle; the method comprising:determining whether a travel state of the vehicle is any one of adeceleration state, a stop state, and a start state, based on adetection result of an internal sensor of the vehicle; and displayingthe information corresponding to each of the deceleration state, thestop state, and the start state, based on a determination result;wherein: in response to the determination that the vehicle is in thedeceleration state, displaying on the display unit the informationincluding a display moving from an upper side to a lower side along avertical direction of the vehicle.
 4. The method according to claim 3,wherein displaying on the display unit the information including thedisplay, when speed of the vehicle is equal to a prescribed value orless.